Method of Forming a Workpiece

ABSTRACT

A method of forming a ceramic metal composite workpiece comprises a step of providing a forming assembly with first and second shaping surfaces that together form a chamber. The chamber is shaped substantially similar to a desired external geometry of a green body of the workpiece, and at least one of the surfaces comprises a pressing mechanism adapted to move the surface with respect to the other surface. The method also comprises placing into the chamber a malleable composite material and an insert comprising a shape substantially similar to a desired internal surface geometry of the green body. The method also comprises a step of pressing the malleable composite material to form the green body such that at least a portion of the malleable composite material flows around at least a portion of the insert to form the green body with the desired external and internal surface geometries.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application Ser. No. 12/098,934 which is a continuation of Ser. No. 12/051,689 which is a continuation-in-part of U.S. patent application Ser. No. 12/051,586 which is a continuation of U.S. patent application Ser. No. 12/021,051 which is a continuation-in-part of U.S. patent application Ser. No. 12/021,019 which was a continuation-in-part of U.S. patent application Ser. No. 11/971,965 which is a continuation of U.S. patent application Ser. No. 11/947,644, which was a continuation-in-part of U.S. patent application Ser. No. 11/844,586. U.S. patent application Ser. No. 11/844,586 is a continuation-in-part of U.S. patent application Ser. No. 11/829,761. U.S. patent application Ser. No. 11/829,761 is a continuation-in-part of U.S. patent application Ser. No. 11/773,271. U.S. patent application Ser. No. 11/773,271 is a continuation-in-part of U.S. patent application Ser. No. 11/766,903. U.S. patent application Ser. No. 11/766,903 is a continuation of U.S. patent application Ser. No. 11/766,865. U.S. patent application Ser. No. 11/766,865 is a continuation-in-part of U.S. patent application Ser. No. 11/742,304. U.S. patent application Ser. No. 11/742,304 is a continuation of U.S. patent application Ser. No. 11/742,261. U.S. patent application Ser. No. 11/742,261 is a continuation-in-part of U.S. patent application Ser. No. 11/464,008. U.S. patent application Ser. No. 11/464,008 is a continuation-in-part of U.S. patent application Ser. No. 11/463,998. U.S. patent application Ser. No. 11/463,998 is a continuation-in-part of U.S. patent application Ser. No. 11/463,990. U.S. patent application Ser. No. 11/463,990 is a continuation-in-part of U.S. patent application Ser. No. 11/463,975. U.S. patent application Ser. No. 11/463,975 is a continuation-in-part of U.S. patent application Ser. No. 11/463,962. U.S. patent application Ser. No. 11/463,962 is a continuation-in-part of U.S. patent application Ser. No. 11/463,953. The present application is also a continuation-in-part of U.S. patent application Ser. No. 11/695,672. U.S. patent application Ser. No. 11/695,672 is a continuation-in-part of U.S. patent application Ser. No. 11/686,831. All of these applications are herein incorporated by reference for all that they contain.

BACKGROUND OF THE INVENTION

Formation degradation, such as pavement milling, mining, or excavating, may result in wear on impact resistant picks. Consequently, many efforts have been made to extend the working life of these picks by optimizing the shape of the picks or the materials with which they are made. Examples of such efforts are disclosed in U.S. Pat. No. 4,944,559 to Sionnet et al., U.S. Pat. No. 5,837,071 to Andersson et al., U.S. Pat. No. 5,417,475 to Graham et al., U.S. Pat. No. 6,051,079 to Andersson et al., and U.S. Pat. No. 4,725,098 to Beach, all of which are herein incorporated by reference for all that they contain.

One solution to pick wear resistance includes the use of ceramic metal composite workpiece, such as those constructed from tungsten carbide, other carbides, and/or polycrystalline diamond. U.S. patent application Ser. No. 11/971,965, which is hereby incorporated by reference for all that it contains, was filed on 10 Jan. 2008 by Hall, et al., and was entitled “Pick with interlocked bolster.” This application discloses an embodiment of a carbide bolster comprising a cavity formed in a base end of the bolster and which is interlocked with a rear portion of a pick.

U.S. Pat. No. 3,848,040 to Confer et al., which is herein incorporated by reference for all that it contains, discloses an integrally formed, segmentally removable, composite core means of organic polymer foam and plaster segments. Portions of each of these segments form the external surface of the core means, but the plaster segment or segments form the greater part of such surface that constitutes a cavity-forming surface. This core means cooperates with a vehicle-absorbent mold to define a mold cavity into which is cast a slip of particulate inorganic material in volatile vehicle.

U.S. Pat. Nos. 7,105,111 and 7,011,785, both granted to Bauer et al. and both of which are herein incorporated by reference for all that they contain, disclose processes for producing hollow bodies comprising fibre-reinforced ceramic materials, where cores whose shape corresponds to that of the hollow spaces are produced in a first step.

U.S. Pat. No. 6,274,078 to Dunyak et al., which is herein incorporated by reference for all that it contains, discloses a method of removing a core from a CMC component in which the core was used to form an internal cavity.

U.S. Pat. No. 5,993,725 to Zuk et al., which is herein incorporated by reference for all that it contains, discloses a method of forming hollow bodies of ceramic material suitable for use as the discharge vessels of high intensity discharge lamps that includes forming a fugitive core of substantially pure graphite having a configuration matching the interior configuration of the hollow body.

U.S. Pat. No. 5,255,427 to Hafner, which is herein incorporated by reference for all that it contains, discloses a hollow boy integrally formed of ceramic material and comprising a cavity formed therein and an integral connecting joint including a passage to said cavity at least one side of said cavity being confined by a diaphragm integral thereto.

U.S. Pat. No. 4,834,938 to Pyzik et al., which is herein incorporated by reference for all that it contains, discloses a process for making a composite article without shrinkage, particularly of ceramic and metal wherein the article includes complex internal surfaces or cavities.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the invention, a method of forming a ceramic metal composite workpiece comprises a step of providing a forming assembly with first and second shaping surfaces that together form a chamber. The chamber is shaped substantially similar to a desired external geometry of a green body of the workpiece, and at least one of the surfaces comprises a pressing mechanism adapted to move the surface with respect to the other surface. The method further comprises a step of placing into the chamber a malleable composite material and an insert comprising a shape substantially similar to a desired internal surface geometry of the green body. The method also comprises a step of pressing the malleable composite material to form the green body such that at least a portion of the malleable composite material flows around at least a portion of the insert to form the green body with the desired external and internal surface geometries.

The method may comprise an additional step of sintering the green body. The green body may be sintered under pressure. During the sintering process the insert may vaporize and/or melt out of the green body. Following sintering the workpiece may be brazed to an impact tip comprising a superhard material disposed on an impact surface of the tip. The step of pressing the malleable composite material may comprise pressing the material with a pressure of at least 5000 psi.

The insert may comprise a vaporization temperature of 600° C. or lower. The insert may comprise a diffusion barrier. The insert may comprise a material selected from the group consisting of plastics, metals, waxes, polymers, or combinations thereof. At least a portion of the insert may have a shape comprising a generally spherical geometry, a generally hourglass-shaped geometry, a generally cone-shaped geometry, or combinations thereof. The insert may comprise at least one ledge, lip, taper, protrusion, ridge, prong, slot, or combinations thereof. The insert may comprise inner and outer diameters, and may comprise a thread form disposed on an outer surface of the insert.

The composite material may comprise a tungsten carbide. In some embodiments the composite material may comprise a polycrystalline diamond. The malleable composite material may comprise a sintering temperature of at least 1300° C.

The green body may comprise a ledge, lip, taper, protrusion, ridge, slot, or combinations thereof. The insert may be placed into the chamber prior to placing the malleable composite material in the chamber. In some embodiments the malleable composite material may be placed into the chamber prior to placing the insert in the chamber. At least one of the shaping surfaces may comprise an insert connection and/or release mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional diagram of an embodiment of a milling machine.

FIG. 2 is a cross-sectional diagram of an embodiment of an impact resistant pick.

FIG. 3 is a cross-sectional diagram of an embodiment of a forming assembly.

FIG. 4 is a cross-sectional diagram of another embodiment of a forming assembly.

FIG. 5 is a cross-sectional diagram of another embodiment of a forming assembly.

FIG. 6 is a cross-sectional diagram of another embodiment of a forming assembly.

FIG. 7 is a cross-sectional diagram of an embodiment of a workpiece.

FIG. 8 is a cross-sectional diagram of another embodiment of workpiece.

FIG. 9 is a cross-sectional diagram of another embodiment of a forming assembly.

FIG. 10 is a cross-sectional diagram of another embodiment of a forming assembly.

FIG. 11 is a cross-sectional diagram of another embodiment of a forming assembly.

FIG. 12 is a cross-sectional diagram of another embodiment of a workpiece.

FIG. 13 is a cross-sectional diagram of another embodiment of a workpiece.

FIG. 14 is a cross-sectional diagram of another embodiment of a workpiece.

FIG. 15 is a cross-sectional diagram of another embodiment of a workpiece.

FIG. 16 is a cross-sectional diagram of another embodiment of a workpiece.

FIG. 17 is a cross-sectional diagram of another embodiment of a workpiece.

FIG. 18 is a perspective diagram of an embodiment of an insert.

FIG. 19 is a perspective diagram of another embodiment of an insert.

FIG. 20 is a perspective diagram of another embodiment of an insert.

FIG. 21 is a perspective diagram of another embodiment of an insert.

FIG. 22 is a perspective diagram of another embodiment of an insert.

FIG. 23 is a perspective diagram of another embodiment of an insert.

FIG. 24 is a cross-sectional diagram of another embodiment of a workpiece.

FIG. 25 is a cross-sectional diagram of another embodiment of a workpiece.

FIG. 26 is a cross-sectional diagram of another embodiment of a workpiece.

FIG. 27 is a cross-sectional diagram of another embodiment of a workpiece.

FIG. 28 is a cross-sectional diagram of another embodiment of a workpiece.

FIG. 29 is a cross-sectional diagram of another embodiment of a workpiece.

FIG. 30 is a perspective diagram of another embodiment of an insert.

FIG. 31 is a perspective diagram of another embodiment of an insert.

FIG. 32 is a perspective diagram of another embodiment of an insert.

FIG. 33 is a perspective diagram of another embodiment of an insert.

FIG. 34 is a perspective diagram of another embodiment of an insert.

FIG. 35 is a flow-chart illustrating an embodiment of a method of forming a ceramic metal composite workpiece 220.

FIG. 36 is a flow-chart illustrating an embodiment of another method of forming a ceramic metal composite workpiece 220.

DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENT

FIG. 1 is a cross-sectional diagram of an embodiment of a plurality of picks 101 attached to a driving mechanism 103, such as a rotating drum connected to the underside of a pavement milling machine 100. The milling machine 100 may be a cold planer used to degrade manmade formations such as a paved surface 104 prior to the placement of a new layer of pavement. Picks 101 may be attached to the driving mechanism bringing the picks 101 into engagement with the formation. A holder 102, which may be a block, an extension in the block or a combination thereof, is attached to the driving mechanism 103, and the pick 101 is inserted into the holder 102. The holder 102 may hold the pick 101 at an angle offset from the direction of rotation, such that the pick 101 engages the pavement at a preferential angle. In addition to milling machines, the pick 101 may be adapted for use in a downhole rotary drill bit, in a horizontal directional drill bit, in trenching machines, in mining machines, and in coal mining machines. Each pick 101 may be designed for high-impact resistance and long life while milling the paved surface 104.

Referring now to FIG. 2, the pick 101 comprises a rear portion 200 comprising first and second ends 201, 202, and a front portion 235. The front portion 235 comprises an impact tip 208 that is brazed to a carbide bolster 205. The bolster 205 is adapted to interlock with the rear portion 200. The first end 201 of the rear portion 200 may be press fit into a cavity 203 in a base end 204 of a cemented metal carbide bolster 205. A superhard material 206 may be bonded to a cemented metal carbide substrate 207 to form the impact tip 208, which may then be bonded to the bolster 205 opposite the base end 204 of the bolster 205, and opposite the first end 201 of the rear portion 200. In FIG. 2 the rear portion 200 is generally cylindrical. The second end 202 of the rear portion 200 is disposed within a bore 209 of a holder 102, which may comprise an extension 210, a block 211 attached to the driving mechanism 103, or both.

The bolster 205 may comprise tungsten, titanium, tantalum, molybdenum, niobium, cobalt, diamond, polycrystalline diamond, and/or combinations thereof. The super hard material 206 may be a material selected from the group consisting of diamond, monocrystalline diamond, polycrystalline diamond, sintered diamond, chemical deposited diamond, physically deposited diamond, natural diamond, infiltrated diamond, layered diamond, thermally stable diamond, silicon-bonded diamond, metal-bonded diamond, silicon carbide, cubic boron nitride, and combinations thereof. In FIG. 2 the bolster 205 comprises an inwardly protruding catch 237. The bolster 205 is an embodiment of a ceramic metal workpiece 220.

Referring now to FIGS. 3-6, a forming assembly 300 comprises first and second shaping surfaces 301, 302 that together form a chamber 303 shaped substantially similar to a desired external geometry 503 of a green body 304 of a workpiece 220. In FIGS. 3-6 each of the shaping surfaces 301, 302 comprise a pressing mechanism 305 adapted to move the surface 301, 302 with respect to the other surface 302, 301. In some embodiments only one of the shaping surfaces 301, 302 may comprise a pressing mechanism 305. An insert 306 is disposed within the chamber 303 and comprises a shape 410 substantially similar to a desired internal surface geometry 504 of the green body 304. In FIG. 3 a malleable composite material 307 is being placed into the chamber. In FIG. 3 the insert 306 is present in the chamber 303 prior to the addition of the composite material 307 into the chamber 303. The malleable composite material 307 may be a powder or a slurry. The composite material may comprise a plurality of tiny particles of tungsten and carbide or combinations thereof. Discrete particles of tungsten and carbide may be mixed together in the composite material 307, or, in some embodiments, particles may comprise both tungsten and carbide. In some embodiments the composite material 307 may comprise tungsten carbide, tungsten, carbon, silicon, boron, diamond, polycrystalline diamond, or combinations thereof. The malleable composite material 307 may comprise a metal and a non-metal designed to sinter together to form a highly wear-resistant ceramic. FIG. 4 discloses an embodiment of a forming assembly 300 comprising a chamber 303 having an insert 306 and a malleable composite material 307 disposed within it. The first shaping surface 301 has moved towards the second shaping surface 302 as compared to the embodiment of FIG. 3.

FIG. 5 discloses an embodiment of a forming assembly 300 in which the pressing mechanisms 305 of each shaping surface 301, 302 have extended the surfaces 301, 302 towards one another, thereby enclosing the chamber 303. The malleable composite material 307 is being pressed to form a green body 304. Arrows 501 in FIG. 5 disclose at least a portion of the composite material 307 flowing around a convex portion 502 of the insert 306 to form a green body 304 having an internal surface geometry 504 complementary to the insert 306 and an external surface geometry 503 complementary to the chamber 303. The composite material 307 may be pressed with a pressure of at least 5000 psi. In some embodiments, the convex portion 502 may be a lip, an undercut, a shelf, an overhang, a portion of an underside of the insert, or combinations thereof. In some embodiments, the insert may comprise a larger diameter than the a portion of the shaping surface upon which it rests.

In FIG. 6 the first and second shaping surfaces 301, 302 have moved away from one another leaving a green body 304 disposed in the second shaping surface 302 comprising desired external and internal surface geometries 503, 504. In the present embodiment the green body 304 comprises an inwardly protruding catch 237 formed by shaping the green body 304 against the insert 306. The second shaping surface 302 comprises an insert release mechanism 601. The release mechanism 601 is adapted to push the insert 306 away from the shaping surface 302 (in the direction indicated by the arrow 602) while the green body 304 is being removed from the shaping surface 302.

Referring now to FIG. 7, an embodiment of an insert 306 is disclosed disposed within a green body 304 while the green body is being sintered in a sintering oven 701. Heater coils 702 raise the temperature in the oven 701 above a minimum melting and/or vaporization temperature of the insert 306 and below a maximum sintering temperature of the green body 304. In some embodiments the insert may be vaporized or melted at a temperature below a minimum sintering temperature of the green body 304. The insert 306 may comprise a vaporization temperature of 600° C. or lower and the malleable composite material may comprise a sintering temperature of at least 1300° C. The insert 306 in FIG. 7 comprises a diffusion barrier 703 disposed intermediate the insert 306 and the green body 304. The diffusion barrier 703 may prevent diffusion of the insert material into the green body during melting and/or vaporization of the insert 306. The diffusion barrier 703 may have a melting temperature higher than the melting and/or vaporization temperature of the insert material. This characteristic may allow the diffusion barrier 703 to remain in contact with the green body 304 after the insert material has vaporized or melted out of the green body 304 to prevent insert material from diffusing into the green body 304. The barrier 703 may be subsequently melted or vaporized out of the green body 304 either before or during the sintering process. The diffusion barrier 703 may comprise a barrier material comprising AlO₂, boron nitride, or combinations thereof.

Referring now to FIG. 8, a cross-sectional view of a sintered metal composite workpiece 220 discloses the workpiece comprising an inwardly protruding catch 237 and cavity 203 where the insert 306 had previously been positioned. FIG. 8 also discloses an embodiment of an impact tip 208 that may be brazed to the sintered workpiece 220. The workpiece 220 in FIG. 8 may be a metal carbide bolster as disclosed in FIG. 2. In some embodiments of the invention the workpiece 220 may be disposed on a milling machine, mining pick, trencher, vertical shaft impactor, cone crusher, or combinations thereof.

Referring to the pick 101 disclosed in FIG. 2, dimensions of the rear portion 200 and bolster 205 may be important to the function and efficiency of the pick 101. A ratio of a length of the rear portion 200 to a length of the bolster 205 may be from 1.75:1 to 2.5:1. A ratio of a maximum width of the bolster 205 to the outer diameter 217 of the rear portion 200 may be from 1.5:1 to 2.5:1. The first end 201 of the rear portion 200 may be fitted into a cavity 203 of the bolster 205 to a depth of 0.300 to 0.700 inches. The cavity 203 of the bolster 205 may comprise a depth from 0.600 to 1 inch. The rear portion 200 may or may not extend into a full depth of the cavity 203. The rear portion 200 and bolster 205 may also comprise an interference fit from 0.0005 to 0.005 inches. The bolster may comprise a minimum cross-sectional thickness between an internal surface of the cavity 203 and an outside surface of the bolster 205 of 0.200 inches, preferable at least 0.210 inches. Reducing the volume of the bolster 205 may advantageously reduce the cost of the pick 101.

A superhard material 206 may comprise a generally conical shape with an apex. A thickness of the diamond at the apex may be 0.100 to 0.500 inches. The cemented metal carbide substrate 207 may comprise a height of 0.090 to 0.250 inches. The superhard material 206 bonded to the substrate 207 may comprise a substantially pointed geometry with an apex comprising a 0.050 to 0.160 inch radius. Preferably, the interface between the substrate 207 and the superhard material 206 is non-planar, which may help distribute loads on the tip 208 across a larger area of the interface. The side wall of the superhard material may form an included angle with a central axis of the tip between 30 to 60 degrees. In asphalt milling applications, the inventors have discovered that an optimal included angle is 45 degrees, whereas in mining applications the inventors have discovered that an optimal included angle is between 35 and 40 degrees. A tip that may be compatible with the present invention is disclosed in U.S. patent application Ser. No. 11/673,634 to Hall and is currently pending.

The impact tip 208 may be brazed onto the carbide bolster 205 at a braze interface. Braze material used to braze the tip 208 to the bolster 205 may comprise a melting temperature from 700 to 1200 degrees Celsius; preferably the melting temperature is from 800 to 970 degrees Celsius. The braze material may comprise silver, gold, copper nickel, palladium, boron, chromium, silicon, germanium, aluminum, iron, cobalt, manganese, titanium, tin, gallium, vanadium, phosphorus, molybdenum, platinum, or combinations thereof. The braze material may comprise 30 to 62 weight percent palladium, preferable 40 to 50 weight percent palladium. Additionally, the braze material may comprise 30 to 60 weight percent nickel, and 3 to 15 weight percent silicon; preferably the braze material may comprise 47.2 weight percent nickel, 46.7 weight percent palladium, and 6.1 weight percent silicon. Active cooling during brazing may be critical in some embodiments, since the heat from brazing may leave some residual stress in the bond between the carbide substrate 207 and the super hard material 206. The farther away the super hard material is from the braze interface, the less thermal damage is likely to occur during brazing. Increasing the distance between the brazing interface and the super hard material 206, however, may increase the moment on the carbide substrate 207 and increase stresses at the brazing interface upon impact.

Referring now to FIGS. 9-12, FIG. 9 discloses an embodiment of the invention in which the malleable composite material 307 is placed into the chamber 303 prior to placing the insert 306 into the chamber 303. The first shaping surface 301 comprises an insert connection and release mechanism 901. This mechanism 901 connects the insert 306 to the shaping surface 301 during the placing and pressing process. In FIG. 10 at least a portion of the malleable composite material 307 flows around a corner portion 902 of the insert 306 to form a green body 304 with desired external and internal surface geometries 503, 504 while the composite material 307 is being pressed by the forming assembly 300. Arrows 501 indicate the direction of composite material flow. FIG. 11 discloses a green body 304 comprising an embodiment of external and internal surface geometries 503, 504. FIG. 12 discloses a ceramic metal composite workpiece 220 comprising desired external and internal surface geometries 503, 504 and an inwardly protruding catch 237.

FIGS. 13-17 disclose embodiments of green bodies 304 that may be consistent with the current invention and FIGS. 18-23 disclose embodiments of inserts 306 that may be consistent with the current invention especially in connection with forming a green body 304 similar to those depicted most immediately adjacent to each insert 306. Referring now to FIGS. 13 and 18, an embodiment of a green body 304 is disclosed that may be formed using an insert 306 like that disclosed in FIG. 18. The insert 306 may be connected to a frustoconically-shaped shaping surface during the pressing process. The green body 304 comprises a generally planar edge 1301 at the base end 204 of the green body 304.

Referring now to FIGS. 14 and 19, the green body 304 comprises a taper 1401 at the base end 204 of the green body. The insert 306 in FIG. 19 and the cavity 203 in FIG. 14 each comprise a generally hourglass-shaped geometry. The green bodies 304 in FIGS. 13-15 each comprise an inwardly protruding catch 237 formed by forcing the malleable composite material 307 around at least a portion of an insert 306 during the process of forming the green body.

FIGS. 20 and 21 disclose embodiments of inserts 306 that may be compatible with forming a green body 304 similar to the one disclosed in FIG. 15 consistent with the current invention. The inserts 306 in FIGS. 20 and 21 each have a portion 1501 with a shape comprising a generally spherical geometry. In some embodiments of the invention at least a portion of the insert 306 may have a shape comprising a generally spherical geometry, a generally hourglass-shaped geometry, a generally cone-shaped geometry, or combinations thereof. Inserts 306 may comprise a material selected from the group consisting of plastics, metals, waxes, polymers, and combinations thereof.

Referring now to FIGS. 16 and 22, the insert 306 comprises a thread form 2201 disposed on an outer diameter 2202 of the insert 306. The insert 306 of FIG. 22 may be used to form a green body 304 such as is disclosed in FIG. 16 comprising a thread form 2201 on an internal surface 1601 of the green body 304. Such a thread form 2201 on the green body 304 may facilitate threaded connection of a finished ceramic metal composite workpiece 220 to a pick 101 or other degradation device.

Referring now to FIGS. 17 and 23, an embodiment of an insert 306 is disclosed comprising a ledge 2301. The ledge 2301 may form an inwardly protruding catch 237 in a resultant green body 304 as disclosed in FIG. 17. The insert 306 in FIG. 23 also comprises an outward taper 2302 and a constricted outer diameter 2303.

FIGS. 24-29 disclose embodiments of green bodies 304 that may be formed consistent with the current invention. FIGS. 30-34 disclose embodiments of inserts 306 that may be used to form green bodies 304. In FIG. 24 the green body comprises a wedge 2401 disposed within the cavity 203. In FIG. 30 an insert 306 comprises inner and outer diameters 3001, 2202 such that the insert 306 comprises a central recess 3002. The wedge 2401 in the green body 304 may be formed in the central recess 3002 of the insert 306 during the pressing process.

Referring now to FIGS. 25 and 31, the green body comprises tapered slots 2501 created by prongs 3101 on the insert 306. The insert 306 in FIG. 31 also comprises a lip 3102 that may form an inwardly protruding catch 237 in the green body 304.

FIGS. 26 and 32 disclose an embodiment of the invention in which the insert 306 comprises a plurality of slots 3201 and protrusions 3202 adapted to respectively form a plurality of protrusions 3202 and slots 3201 in the green body 304. The insert 306 also comprises a ledge 2301.

FIGS. 27 and 33 disclose an embodiment of the invention in which the insert 306 comprises protrusions 3202 adapted to form recesses 2701 in the inner surface 1601 of the green body 304. FIG. 28 discloses an embodiment of a green body 304 that may be formed consistent with the present invention and which comprises a tapered outer surface 2801. FIGS. 29 and 34 disclose an embodiment of the invention in which the insert 306 comprises protrusions 3202 adapted to form divots 2901 in an inwardly protruding catch 237 of the green body 304.

FIG. 35 discloses a flow-chart of a method 3500 of forming a ceramic metal composite workpiece 220. The method 3500 comprises a step 3501 of providing a forming assembly 300 with first and second shaping surfaces 301, 302 that together form a chamber 303 shaped substantially similar to a desired external geometry 503 of a green body 304 of the workpiece 220, at least one of the shaping surfaces 301, 302 comprising a pressing mechanism 305 adapted to move the surface 301, 302 with respect to the other surface 302, 301. The method 3500 further comprises a step 3502 of placing a malleable composite material 307 together with an insert 306 that comprises a shape substantially similar to a desired internal surface geometry 504 of the green body 304 within the chamber 303. The method 3500 further comprises a step 3503 of pressing the malleable composite material 307 to form the green body 304 such that at least a some of the malleable composite material 307 flows around at least a portion of the insert 306 to form the green body 304 with the desired external and internal surface geometries 503, 504.

Referring now to FIG. 36, the method 3500 may comprise additional steps in addition to step 3501, 3502, and 3503. The method 3500 may comprise a step 3604 of sintering the green body 304. The step of sintering may be done under pressure. In some embodiments the insert 306 may vaporize and/or melts out of the green body 304 during the step 3604 of sintering the green body 304. The method 3500 may further comprise a step 3605 of brazing the sintered workpiece 220 to an impact tip 208 comprising a superhard material 206 disposed on an impact surface of the tip 208.

Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention. 

1. A method of forming a ceramic metal composite workpiece, comprising the steps of: providing a forming assembly with first and second shaping surfaces together forming a chamber shaped substantially similar to a desired external geometry of a green body of the workpiece, and at least one of the surfaces comprising a pressing mechanism adapted to move the surface with respect to the other surface; placing a malleable composite material and an insert comprising a shape substantially similar to a desired internal surface geometry of the green body within the chamber; pressing the malleable composite material to form the green body such that at least a portion of the malleable composite material flows around at least a portion of the insert to form the green body with the desired external and internal surface geometries.
 2. The method of claim 1, wherein the method comprises an additional step of sintering the green body.
 3. The method of claim 2, wherein the step of sintering is done under pressure.
 4. The method of claim 2, wherein the insert vaporizes and/or melts out of the green body during the step of sintering the green body.
 5. The method of claim 2, wherein the method further comprises a step of brazing the sintered workpiece to an impact tip comprising a superhard material disposed on an impact surface of the tip.
 6. The method of claim 1, wherein the step of pressing the malleable composite material comprises pressing the material with a pressure of at least 5000 psi.
 7. The method of claim 1, wherein the insert comprises a vaporization temperature of 600° C. or lower.
 8. The method of claim 1, wherein the insert comprises a diffusion barrier.
 9. The method of claim 1, wherein the insert comprises an insert material selected from the group consisting of plastics, metals, waxes, polymers, and combinations thereof.
 10. The method of claim 1, wherein at least a portion of the insert has a shape comprising a generally spherical geometry, a generally hourglass-shaped geometry, a generally cone-shaped geometry, or combinations thereof.
 11. The method of claim 1, wherein the insert comprises at least one ledge, lip, taper, protrusion, ridge, prong, slot, or combinations thereof.
 12. The method of claim 1, wherein the insert comprises inner and outer diameters.
 13. The method of claim 1, wherein the insert comprises a thread form disposed on an outer surface of the insert.
 14. The method of claim 1, wherein the composite material comprises a tungsten carbide.
 15. The method of claim 1, wherein the composite material comprises a polycrystalline diamond.
 16. The method of claim 1, wherein the malleable composite material comprises a sintering temperature of at least 1300° C.
 17. The method of claim 1, wherein the green body comprises a ledge, lip, taper, protrusion, ridge, slot, or combinations thereof.
 18. The method of claim 1, wherein the insert is placed into the chamber prior to placing the malleable composite material in the chamber.
 19. The method of claim 1, wherein the malleable composite material is placed into the chamber prior to placing the insert in the chamber.
 20. The method of claim 1, wherein at least one of the shaping surfaces comprises an insert connection and/or release mechanism. 